See also

You should always externalize application resources such as images and strings from your
code, so that you can maintain them independently. You should also provide alternative resources for
specific device configurations, by grouping them in specially-named resource directories. At
runtime, Android uses the appropriate resource based on the current configuration. For
example, you might want to provide a different UI layout depending on the screen size or different
strings depending on the language setting.

Once you externalize your application resources, you can access them
using resource IDs that are generated in your project's R class. How to use
resources in your application is discussed in Accessing
Resources. This document shows you how to group your resources in your Android project and
provide alternative resources for specific device configurations.

Grouping Resource Types

You should place each type of resource in a specific subdirectory of your project's
res/ directory. For example, here's the file hierarchy for a simple project:

As you can see in this example, the res/ directory contains all the resources (in
subdirectories): an image resource, two layout resources, mipmap/ directories for launcher
icons, and a string resource file. The resource
directory names are important and are described in table 1.

XML files that define tween
animations. (Property animations can also be saved in this directory, but
the animator/ directory is preferred for property animations to distinguish between the two
types.)

However, if you need access to original file names and file hierarchy, you might consider
saving some resources in the assets/ directory (instead of res/raw/). Files in assets/ are not given a
resource ID, so you can read them only using AssetManager.

values/

XML files that contain simple values, such as strings, integers, and colors.

Whereas XML resource files in other res/ subdirectories define a single resource
based on the XML filename, files in the values/ directory describe multiple resources.
For a file in this directory, each child of the <resources> element defines a single
resource. For example, a <string> element creates an
R.string resource and a <color> element creates an R.color
resource.

Because each resource is defined with its own XML element, you can name the file
whatever you want and place different resource types in one file. However, for clarity, you might
want to place unique resource types in different files. For example, here are some filename
conventions for resources you can create in this directory:

For more information about certain types of resources, see the Resource Types documentation.

The resources that you save in the subdirectories defined in table 1 are your "default"
resources. That is, these resources define the default design and content for your application.
However, different types of Android-powered devices might call for different types of resources.
For example, if a device has a larger than normal screen, then you should provide
different layout resources that take advantage of the extra screen space. Or, if a device has a
different language setting, then you should provide different string resources that translate the
text in your user interface. To provide these different resources for different device
configurations, you need to provide alternative resources, in addition to your default
resources.

Providing Alternative Resources

Figure 1. Two different devices, each using different layout resources.

Almost every application should provide alternative resources to support specific device
configurations. For instance, you should include alternative drawable resources for different
screen densities and alternative string resources for different languages. At runtime, Android
detects the current device configuration and loads the appropriate
resources for your application.

To specify configuration-specific alternatives for a set of resources:

Create a new directory in res/ named in the form <resources_name>-<config_qualifier>.

<resources_name> is the directory name of the corresponding default
resources (defined in table 1).

<qualifier> is a name that specifies an individual configuration
for which these resources are to be used (defined in table 2).

You can append more than one <qualifier>. Separate each
one with a dash.

Caution: When appending multiple qualifiers, you must
place them in the same order in which they are listed in table 2. If the qualifiers are ordered
wrong, the resources are ignored.

Save the respective alternative resources in this new directory. The resource files must be
named exactly the same as the default resource files.

The hdpi qualifier indicates that the resources in that directory are for devices with a
high-density screen. The images in each of these drawable directories are sized for a specific
screen density, but the filenames are exactly
the same. This way, the resource ID that you use to reference the icon.png or background.png image is always the same, but Android selects the
version of each resource that best matches the current device, by comparing the device
configuration information with the qualifiers in the resource directory name.

Android supports several configuration qualifiers and you can
add multiple qualifiers to one directory name, by separating each qualifier with a dash. Table 2
lists the valid configuration qualifiers, in order of precedence—if you use multiple
qualifiers for a resource directory, you must add them to the directory name in the order they
are listed in the table.

Table 2. Configuration qualifier
names.

Configuration

Qualifier Values

Description

MCC and MNC

Examples:mcc310mcc310-mnc004mcc208-mnc00
etc.

The mobile country code (MCC), optionally followed by mobile network code (MNC)
from the SIM card in the device. For example, mcc310 is U.S. on any carrier,
mcc310-mnc004 is U.S. on Verizon, and mcc208-mnc00 is France on
Orange.

If the device uses a radio connection (GSM phone), the MCC and MNC values come
from the SIM card.

You can also use the MCC alone (for example, to include country-specific legal
resources in your application). If you need to specify based on the language only, then use the
language and region qualifier instead (discussed next). If you decide to use the MCC and
MNC qualifier, you should do so with care and test that it works as expected.

Also see the configuration fields mcc, and mnc, which indicate the current mobile country code
and mobile network code, respectively.

Language and region

Examples:enfren-rUSfr-rFRfr-rCA
etc.

The language is defined by a two-letter ISO
639-1 language code, optionally followed by a two letter
ISO
3166-1-alpha-2 region code (preceded by lowercase "r").

The codes are not case-sensitive; the r prefix is used to
distinguish the region portion.
You cannot specify a region alone.

This can change during the life
of your application if the user changes his or her language in the system settings. See Handling Runtime Changes for information about
how this can affect your application during runtime.

See Localization for a complete guide to localizing
your application for other languages.

Also see the locale configuration field, which
indicates the current locale.

Note: To enable right-to-left layout features
for your app, you must set supportsRtl to "true" and set targetSdkVersion to 17 or higher.

Added in API level 17.

smallestWidth

sw<N>dp

Examples:sw320dpsw600dpsw720dp
etc.

The fundamental size of a screen, as indicated by the shortest dimension of the available
screen area. Specifically, the device's smallestWidth is the shortest of the screen's available
height and width (you may also think of it as the "smallest possible width" for the screen). You can
use this qualifier to ensure that, regardless of the screen's current orientation, your
application has at least <N> dps of width available for its UI.

For example, if your layout requires that its smallest dimension of screen area be at
least 600 dp at all times, then you can use this qualifer to create the layout resources, res/layout-sw600dp/. The system will use these resources only when the smallest dimension of
available screen is at least 600dp, regardless of whether the 600dp side is the user-perceived
height or width. The smallestWidth is a fixed screen size characteristic of the device; the
device's smallestWidth does not change when the screen's orientation changes.

The smallestWidth of a device takes into account screen decorations and system UI. For
example, if the device has some persistent UI elements on the screen that account for space along
the axis of the smallestWidth, the system declares the smallestWidth to be smaller than the actual
screen size, because those are screen pixels not available for your UI. Thus, the value you use
should be the actual smallest dimension required by your layout (usually, this value is the
"smallest width" that your layout supports, regardless of the screen's current orientation).

Some values you might use here for common screen sizes:

320, for devices with screen configurations such as:

240x320 ldpi (QVGA handset)

320x480 mdpi (handset)

480x800 hdpi (high-density handset)

480, for screens such as 480x800 mdpi (tablet/handset).

600, for screens such as 600x1024 mdpi (7" tablet).

720, for screens such as 720x1280 mdpi (10" tablet).

When your application provides multiple resource directories with different values for
the smallestWidth qualifier, the system uses the one closest to (without exceeding) the
device's smallestWidth.

For more information about designing for different screens and using this
qualifier, see the Supporting
Multiple Screens developer guide.

Available width

w<N>dp

Examples:w720dpw1024dp
etc.

Specifies a minimum available screen width, in dp units at which the resource
should be used—defined by the <N> value. This
configuration value will change when the orientation
changes between landscape and portrait to match the current actual width.

When your application provides multiple resource directories with different values
for this configuration, the system uses the one closest to (without exceeding)
the device's current screen width. The
value here takes into account screen decorations, so if the device has some
persistent UI elements on the left or right edge of the display, it
uses a value for the width that is smaller than the real screen size, accounting
for these UI elements and reducing the application's available space.

Added in API level 13.

Also see the screenWidthDp
configuration field, which holds the current screen width.

For more information about designing for different screens and using this
qualifier, see the Supporting
Multiple Screens developer guide.

Available height

h<N>dp

Examples:h720dph1024dp
etc.

Specifies a minimum available screen height, in "dp" units at which the resource
should be used—defined by the <N> value. This
configuration value will change when the orientation
changes between landscape and portrait to match the current actual height.

When your application provides multiple resource directories with different values
for this configuration, the system uses the one closest to (without exceeding)
the device's current screen height. The
value here takes into account screen decorations, so if the device has some
persistent UI elements on the top or bottom edge of the display, it uses
a value for the height that is smaller than the real screen size, accounting
for these UI elements and reducing the application's available space. Screen
decorations that are not fixed (such as a phone status bar that can be
hidden when full screen) are not accounted for here, nor are
window decorations like the title bar or action bar, so applications must be prepared to
deal with a somewhat smaller space than they specify.

Added in API level 13.

Also see the screenHeightDp
configuration field, which holds the current screen width.

For more information about designing for different screens and using this
qualifier, see the Supporting
Multiple Screens developer guide.

Screen size

smallnormallargexlarge

small: Screens that are of similar size to a
low-density QVGA screen. The minimum layout size for a small screen
is approximately 320x426 dp units. Examples are QVGA low-density and VGA high
density.

normal: Screens that are of similar size to a
medium-density HVGA screen. The minimum
layout size for a normal screen is approximately 320x470 dp units. Examples
of such screens a WQVGA low-density, HVGA medium-density, WVGA
high-density.

large: Screens that are of similar size to a
medium-density VGA screen.
The minimum layout size for a large screen is approximately 480x640 dp units.
Examples are VGA and WVGA medium-density screens.

xlarge: Screens that are considerably larger than the traditional
medium-density HVGA screen. The minimum layout size for an xlarge screen
is approximately 720x960 dp units. In most cases, devices with extra-large
screens would be too large to carry in a pocket and would most likely
be tablet-style devices. Added in API level 9.

Note: Using a size qualifier does not imply that the
resources are only for screens of that size. If you do not provide alternative
resources with qualifiers that better match the current device configuration, the system may use
whichever resources are the best match.

Caution: If all your resources use a size qualifier that
is larger than the current screen, the system will not use them and your
application will crash at runtime (for example, if all layout resources are tagged with the xlarge qualifier, but the device is a normal-size screen).

Also see the screenLayout configuration field,
which indicates whether the screen is small, normal,
or large.

Screen aspect

longnotlong

long: Long screens, such as WQVGA, WVGA, FWVGA

notlong: Not long screens, such as QVGA, HVGA, and VGA

Added in API level 4.

This is based purely on the aspect ratio of the screen (a "long" screen is wider). This
is not related to the screen orientation.

Also see the screenLayout configuration field,
which indicates whether the screen is long.

Screen orientation

portland

port: Device is in portrait orientation (vertical)

land: Device is in landscape orientation (horizontal)

This can change during the life of your application if the user rotates the
screen. See Handling Runtime Changes for information about
how this affects your application during runtime.

Also see the orientation configuration field,
which indicates the current device orientation.

UI mode

cardesktelevisionappliancewatch

car: Device is displaying in a car dock

desk: Device is displaying in a desk dock

television: Device is displaying on a television, providing
a "ten foot" experience where its UI is on a large screen that the
user is far away from, primarily oriented around DPAD or other
non-pointer interaction

This can change during the life of your application if the user places the device in a
dock. You can enable or disable some of these modes using UiModeManager. See Handling Runtime Changes for
information about how this affects your application during runtime.

Night mode

nightnotnight

night: Night time

notnight: Day time

Added in API level 8.

This can change during the life of your application if night mode is left in
auto mode (default), in which case the mode changes based on the time of day. You can enable
or disable this mode using UiModeManager. See Handling Runtime Changes for information about how this affects your
application during runtime.

nodpi: This can be used for bitmap resources that you do not want to be scaled
to match the device density.

tvdpi: Screens somewhere between mdpi and hdpi; approximately 213dpi. This is
not considered a "primary" density group. It is mostly intended for televisions and most
apps shouldn't need it—providing mdpi and hdpi resources is sufficient for most apps and
the system will scale them as appropriate. This qualifier was introduced with API level 13.

There is a 3:4:6:8:12:16 scaling ratio between the six primary densities (ignoring the
tvdpi density). So, a 9x9 bitmap in ldpi is 12x12 in mdpi, 18x18 in hdpi, 24x24 in xhdpi and so on.

If you decide that your image resources don't look good enough on a television or
other certain devices and want to try tvdpi resources, the scaling factor is 1.33*mdpi. For
example, a 100px x 100px image for mdpi screens should be 133px x 133px for tvdpi.

Note: Using a density qualifier does not imply that the
resources are only for screens of that density. If you do not provide alternative
resources with qualifiers that better match the current device configuration, the system may use
whichever resources are the best match.

See Supporting Multiple
Screens for more information about how to handle different screen densities and how Android
might scale your bitmaps to fit the current density.

Touchscreen type

notouchfinger

notouch: Device does not have a touchscreen.

finger: Device has a touchscreen that is intended to
be used through direction interaction of the user's finger.

Also see the touchscreen configuration field,
which indicates the type of touchscreen on the device.

Keyboard availability

keysexposedkeyshiddenkeyssoft

keysexposed: Device has a keyboard available. If the device has a
software keyboard enabled (which is likely), this may be used even when the hardware keyboard is
not exposed to the user, even if the device has no hardware keyboard. If no software
keyboard is provided or it's disabled, then this is only used when a hardware keyboard is
exposed.

keyshidden: Device has a hardware keyboard available but it is
hidden and the device does not have a software keyboard enabled.

If you provide keysexposed resources, but not keyssoft
resources, the system uses the keysexposed resources regardless of whether a
keyboard is visible, as long as the system has a software keyboard enabled.

This can change during the life of your application if the user opens a hardware
keyboard. See Handling Runtime Changes for information about how
this affects your application during runtime.

Also see the configuration fields hardKeyboardHidden and keyboardHidden, which indicate the visibility of a hardware
keyboard and and the visibility of any kind of keyboard (including software), respectively.

Primary text input method

nokeysqwerty12key

nokeys: Device has no hardware keys for text input.

qwerty: Device has a hardware qwerty keyboard, whether it's visible to the
user
or not.

12key: Device has a hardware 12-key keyboard, whether it's visible to the user
or not.

Also see the keyboard configuration field,
which indicates the primary text input method available.

Navigation key availability

navexposednavhidden

navexposed: Navigation keys are available to the user.

navhidden: Navigation keys are not available (such as behind a closed
lid).

This can change during the life of your application if the user reveals the navigation
keys. See Handling Runtime Changes for
information about how this affects your application during runtime.

Also see the navigationHidden configuration
field, which indicates whether navigation keys are hidden.

Primary non-touch navigation method

nonavdpadtrackballwheel

nonav: Device has no navigation facility other than using the
touchscreen.

dpad: Device has a directional-pad (d-pad) for navigation.

trackball: Device has a trackball for navigation.

wheel: Device has a directional wheel(s) for navigation (uncommon).

Also see the navigation configuration field,
which indicates the type of navigation method available.

Platform Version (API level)

Examples:v3v4v7
etc.

The API level supported by the device. For example, v1 for API level
1 (devices with Android 1.0 or higher) and v4 for API level 4 (devices with Android
1.6 or higher). See the Android API levels document for more information
about these values.

Note: Some configuration qualifiers have been added since Android
1.0, so not all versions of Android support all the qualifiers. Using a new qualifier implicitly
adds the platform version qualifier so that older devices are sure to ignore it. For example, using
a w600dp qualifier will automatically include the v13 qualifier, because
the available-width qualifier was new in API level 13. To avoid any issues, always include a set of
default resources (a set of resources with no qualifiers). For more information, see the
section about Providing the Best Device Compatibility with
Resources.

Qualifier name rules

Here are some rules about using configuration qualifier names:

You can specify multiple qualifiers for a single set of resources, separated by dashes. For
example, drawable-en-rUS-land applies to US-English devices in landscape
orientation.

Alternative resource directories cannot be nested. For example, you cannot have
res/drawable/drawable-en/.

Values are case-insensitive. The resource compiler converts directory names
to lower case before processing to avoid problems on case-insensitive
file systems. Any capitalization in the names is only to benefit readability.

Only one value for each qualifier type is supported. For example, if you want to use
the same drawable files for Spain and France, you cannot have a directory named
drawable-rES-rFR/. Instead you need two resource directories, such as
drawable-rES/ and drawable-rFR/, which contain the appropriate files.
However, you are not required to actually duplicate the same files in both locations. Instead, you
can create an alias to a resource. See Creating
alias resources below.

After you save alternative resources into directories named with
these qualifiers, Android automatically applies the resources in your application based on the
current device configuration. Each time a resource is requested, Android checks for alternative
resource directories that contain the requested resource file, then finds the
best-matching resource (discussed below). If there are no alternative resources that match
a particular device configuration, then Android uses the corresponding default resources (the
set of resources for a particular resource type that does not include a configuration
qualifier).

Creating alias resources

When you have a resource that you'd like to use for more than one device
configuration (but do not want to provide as a default resource), you do not need to put the same
resource in more than one alternative resource directory. Instead, you can (in some cases) create an
alternative
resource that acts as an alias for a resource saved in your default resource directory.

Note: Not all resources offer a mechanism by which you can
create an alias to another resource. In particular, animation, menu, raw, and other unspecified
resources in the xml/ directory do not offer this feature.

For example, imagine you have an application icon, icon.png, and need unique version of
it for different locales. However, two locales, English-Canadian and French-Canadian, need to
use the same version. You might assume that you need to copy the same image
into the resource directory for both English-Canadian and French-Canadian, but it's
not true. Instead, you can save the image that's used for both as icon_ca.png (any
name other than icon.png) and put
it in the default res/drawable/ directory. Then create an icon.xml file in res/drawable-en-rCA/ and res/drawable-fr-rCA/ that refers to the icon_ca.png
resource using the <bitmap> element. This allows you to store just one version of the
PNG file and two small XML files that point to it. (An example XML file is shown below.)

Drawable

To create an alias to an existing drawable, use the <bitmap> element.
For example:

If you save this file as icon.xml (in an alternative resource directory, such as
res/drawable-en-rCA/), it is compiled into a resource that you
can reference as R.drawable.icon, but is actually an alias for the R.drawable.icon_ca resource (which is saved in res/drawable/).

Layout

To create an alias to an existing layout, use the <include>
element, wrapped in a <merge>. For example:

Providing the Best Device Compatibility with Resources

In order for your application to support multiple device configurations, it's very important that
you always provide default resources for each type of resource that your application uses.

For example, if your application supports several languages, always include a values/ directory (in which your strings are saved) without a language and region qualifier. If you instead put all your string files
in directories that have a language and region qualifier, then your application will crash when run
on a device set to a language that your strings do not support. But, as long as you provide default
values/ resources, then your application will run properly (even if the user doesn't
understand that language—it's better than crashing).

Likewise, if you provide different layout resources based on the screen orientation, you should
pick one orientation as your default. For example, instead of providing layout resources in layout-land/ for landscape and layout-port/ for portrait, leave one as the default, such as
layout/ for landscape and layout-port/ for portrait.

Providing default resources is important not only because your application might run on a
configuration you had not anticipated, but also because new versions of Android sometimes add
configuration qualifiers that older versions do not support. If you use a new resource qualifier,
but maintain code compatibility with older versions of Android, then when an older version of
Android runs your application, it will crash if you do not provide default resources, because it
cannot use the resources named with the new qualifier. For example, if your minSdkVersion is set to 4, and you qualify all of your drawable resources using night mode (night or notnight, which were added in API
Level 8), then an API level 4 device cannot access your drawable resources and will crash. In this
case, you probably want notnight to be your default resources, so you should exclude that
qualifier so your drawable resources are in either drawable/ or drawable-night/.

So, in order to provide the best device compatibility, always provide default
resources for the resources your application needs to perform properly. Then create alternative
resources for specific device configurations using the configuration qualifiers.

There is one exception to this rule: If your application's minSdkVersion is 4 or
greater, you do not need default drawable resources when you provide alternative drawable
resources with the screen density qualifier. Even without default
drawable resources, Android can find the best match among the alternative screen densities and scale
the bitmaps as necessary. However, for the best experience on all types of devices, you should
provide alternative drawables for all three types of density.

How Android Finds the Best-matching Resource

When you request a resource for which you provide alternatives, Android selects which
alternative resource to use at runtime, depending on the current device configuration. To
demonstrate how Android selects an alternative resource, assume the following drawable directories
each contain different versions of the same images:

Exception: Screen pixel density is the one qualifier that is not
eliminated due to a contradiction. Even though the screen density of the device is hdpi,
drawable-port-ldpi/ is not eliminated because every screen density is
considered to be a match at this point. More information is available in the Supporting Multiple
Screens document.

Pick the (next) highest-precedence qualifier in the list (table 2).
(Start with MCC, then move down.)

Do any of the resource directories include this qualifier?

If No, return to step 2 and look at the next qualifier. (In the example,
the answer is "no" until the language qualifier is reached.)

If Yes, continue to step 4.

Eliminate resource directories that do not include this qualifier. In the example, the system
eliminates all the directories that do not include a language qualifier:

Exception: If the qualifier in question is screen pixel density,
Android selects the option that most closely matches the device screen density.
In general, Android prefers scaling down a larger original image to scaling up a smaller
original image. See Supporting Multiple
Screens.

Go back and repeat steps 2, 3, and 4 until only one directory remains. In the example, screen
orientation is the next qualifier for which there are any matches.
So, resources that do not specify a screen orientation are eliminated:

drawable-en/
drawable-en-port/
drawable-en-notouch-12key/

The remaining directory is drawable-en-port.

Though this procedure is executed for each resource requested, the system further optimizes
some aspects. One such optimization is that once the device configuration is known, it might
eliminate alternative resources that can never match. For example, if the configuration
language is English ("en"), then any resource directory that has a language qualifier set to
something other than English is never included in the pool of resources checked (though a
resource directory without the language qualifier is still included).

When selecting resources based on the screen size qualifiers, the system will use resources
designed for a screen smaller than the current screen if there are no resources that better match
(for example, a large-size screen will use normal-size screen resources if necessary). However, if
the only available resources are larger than the current screen, the system will
not use them and your application will crash if no other resources match the device
configuration (for example, if all layout resources are tagged with the xlarge qualifier,
but the device is a normal-size screen).

Note: The precedence of the qualifier (in table 2) is more important
than the number of qualifiers that exactly match the device. For example, in step 4 above, the last
choice on the list includes three qualifiers that exactly match the device (orientation, touchscreen
type, and input method), while drawable-en has only one parameter that matches
(language). However, language has a higher precedence than these other qualifiers, so
drawable-port-notouch-12key is out.